Connecting pairs of points from separate plots

Question

I have two scatter plots coming from one single csv file.

no,id,x,y,x_proj,y_proj
1,1,565,417,565.6,393.3
1,2,315,234,334.8,193
1,3,949,355,944.8,346.3

I would like to link each point that has the same id. Is there a simple way to do that ?

Pictures of what I have :

Picture of what I want :

The code I have so far :

\documentclass{article}
\usepackage{filecontents}
\usepackage{pgfplots}

\begin{document}

\begin{filecontents*}{data.csv}
no,id,x,y,x_proj,y_proj
1,1,565,417,565.6,393.3
1,2,315,234,334.8,193
1,3,949,355,944.8,346.3
\end{filecontents*}

\begin{tikzpicture}
\begin{axis}[
    enlargelimits=false,
    xmin=0, xmax=1280,
    ymin=0, ymax=720,
]
\addplot[
    only marks,
    scatter,
    mark=*,
    mark size=2pt]
    table[meta index=1, col sep=comma, x=x,y=y]{data.csv};
\addplot[
    only marks,
    scatter,
    mark=*,
    mark size=2pt]
    table[meta index=1, col sep=comma, x=x_proj,y=y_proj]{data.csv};
\end{axis}
\end{tikzpicture}

\end{document}

Thanks in advance,

Answer 1

This can be done by adding a coordinate to each point. Then you can simply connect the corresponding coordinates.

For more details please have a look at the comments in the code.
(The code was adjusted from https://tex.stackexchange.com/a/335625)

% used PGFPlots v1.15
\begin{filecontents*}{data.csv}
no,id,x,y,x_proj,y_proj
1,1,565,417,565.6,393.3
1,2,315,234,334.8,193
1,3,949,355,944.8,346.3
\end{filecontents*}
\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
    \pgfplotstableread[col sep=comma]{data.csv}{\loadedtable}
        % store number of data points
        \pgfplotstablegetrowsof{\loadedtable}
        \pgfmathtruncatemacro{\N}{\pgfplotsretval-1}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
%        % (commented to enlarge the distance between the points)
%        enlargelimits=false,
%        xmin=0, xmax=1280,
%        ymin=0, ymax=720,
    ]

        \addplot[
            only marks,
            scatter,
            mark=*,
%            % -------------------------------------------------------------
%            % comment this block to hide names of the coords
%            % -----
%            % just for debugging purposes you can draw the names of the
%            % coordinates to check that everything is right/fine
%            nodes near coords=a\coordindex,
%            % increase the distance of the nodes a bit
%            nodes near coords align={above=1ex},
%            % -------------------------------------------------------------
        ] table [x=x,y=y,meta index=1] {\loadedtable}
            % set a coordinate on each data point
            \foreach \i in {0,...,\N} {
                coordinate [pos=\i/\N] (a\i)
            }
        ;

        \addplot[
            only marks,
            scatter,
            mark=*,
%            % -------------------------------------------------------------
%            nodes near coords=b\coordindex,
%            nodes near coords align={below=1ex},
%            % -------------------------------------------------------------
        ] table [x=x_proj,y=y_proj,meta index=1] {\loadedtable}
            % set a coordinate on each data point
            \foreach \i in {0,...,\N} {
                coordinate [pos=\i/\N] (b\i)
            }
        ;
    \end{axis}

        % now draw the connecting lines
        \foreach \i in {0,...,\N} {
            \draw (a\i) -- (b\i);
        }
\end{tikzpicture}
\end{document}